When building a new robot, it's rare that it works exactly right the first time.

Sometimes there are a few small
tweaks that the machine could benefit
from; sometimes you discover that the
design just doesn't work for you and
you need to start from scratch. Other
times, the general design is solid but
for one reason or another, needs a
substantial amount of modification.

Reptar — one of my team’s 1 lb
combat robots — is an example of
the latter.

Reptar started when a friend of
mine decided he wanted a fighting
robot for himself. He didn't just want
to borrow one. He wanted to learn
how to use the tools, work on the
design, and make as much of it as
possible himself. For a first robot, I
One major hazard of this build
style is that it's very difficult to
accurately predict weights ahead of
time. As a result of this, the combat-ready Reptar had to have a substantial
amount of material removed from the
chassis after the majority of assembly
was complete.

A portion of the weight issues
came from using scavenged materials
as they tended to be whatever
thickness was available, which often
meant it was far thicker than it
needed to be. The other side of the
issue is that when you don't have a
pre-determined layout, you have to
leave a good deal of extra space to
make sure you have room for all of
the electronics. The larger footprint
combined with random thicknesses of
material meant that the robot started
out dramatically overweight.

Once it made weight, Reptar
performed quite well. The large
hinged flipper proved to be well-suited
to the local arena allowing it to either